Packet-switched System For Communication Network Node - Patent 7639679

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Packet-switched System For Communication Network Node - Patent 7639679 Powered By Docstoc
					
				
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Description: The invention is related to the field of telecommunication networks and concerns the switching systems used in network nodes.BACKGROUNDThe invention specifically concerns switching systems capable of processing data organised in packets (packet switching). It also concerns the so-called "multiservice" switching systems, i.e., systems that are capable of performing packetswitching while also being capable of processing data organised in different transmission formats (circuit switching), typically data organised in time-division multiplexing (TDM) in compliance with the SDH or SONET protocols or even ODU ("Optical DataUnit").Here the term "packet" refers to any data set grouping transmit data information according to a pre-established format (called "payload") and auxiliary data contained e.g. in a packet header. The header specifically contains an indication of thedestination of the packet and generally a service quality class. The indication may be an explicit destination address or a "label" representative of that destination. The most common packet formats include the IP (Internet Protocol), MPLS or Ethernetpackets that have a variable size and the ATM cells that have a fixed size.It should be noted that a network comprises multiple nodes interconnected by transmission links. A node is frequently connected to various other nodes and then integrates routing functions to selectively route data carried by signals receivedfrom upstream links to other downstream links depending on the respective destinations of the data. Certain nodes have access functions allowing to introduce data in the network and/or to extract data from the network.To perform a routing function a node is equipped with a switching system or more simply with a "switch". A switching system comprises multiple input ports connected by upstream links to transmitters of user stations or to other nodes as well asmultiple output ports connected by downstream links to receivers of other user station